I am interested in using laser engraving to lay out my PCBs. So I have a couple of questions to that end.
I am nit looking for the laser to cut through the copper, but rather to coat the copper, then have the engraver cut away the coating so I can then etch the circuit.
My questions:
What type of specs should I be looking for in the engraver? Position accuracy and cut width I assume.
What are reasonable specs for each of those?
Any other specs I should look at?
What pitfalls might I have?
I worry about the difficulty of making 2 sided boards
Are there any DIY laser engravers that are known to work well with Kicad? Any to avoid?
Never heard of doing what you’re wanting to do but…
I’ve etched PCB’s in the long-ago past but always used a copper-coated (pre-made) board. The cost is usually less than $10 for quantity of 10 (Amazon has many, single and double sided boards: Link to example).
Several different methods to do Etching - many Youtube videos to watch.
As far as Engraving: it’s about the ‘Bit’ used in a machine and I use a CNC mill. I don’t like using Engraving bits. I prefer End-Mill bits but, the process and machine are the same. Bit choice is a personal preference. Why? As follows:
Engraving bits are tapered and controlling the trace width is the challenge (the deeper the bit goes, the narrower the trace) so, setup is important.
End-Mill bits are straight-sided so, no matter the depth, the traces are constant.
A PCB milling machine is about $200+ on Amazon. Link to Example.
Software: after designing your circuit in Kicad, export the gerber files, load them into software and take it from there… Depends on the software.
I use CopperCam to take the Gerbers and export the Milling (or etching) Gcode. (CopperCam is free to use it’s limited version. Link to CopperCam).
My comment was less about Laser cutting through the copper but more relevant to any coatings. Never heard of folks coating their board until after milling/etching. Regardless of coating, you need to cut through the Copper (either by Etching, Milling or Engraving).
The Machine I linked is typical of these types of machines. However, I use a CNC Milling machine (similar but not the same).
Also, you can attach a Laser cutter (or a Drill-Motor) to a 3D printer and do the same process. I rigged up one of my 3D printers to try this - worked okay but, it was only a test since I have a several thousand-dollar CNC mill. Instead of using a drill-motor, I rigged up a Dremel Hand tool.
[EDIT] SMD or Through Holes - not a problem…
Photo showing results of final testing to dial-in bit, feed and speed on my pcb milling…
I’ve done this with spray paint and a 25W CO2 laser engraver. I think you could probably use one of those cheap purple lasers on Amazon as well. I wouldn’t worry much about accuracy specs, you’re likely to be more limited by your etching. You just convert the gerber to a bitmap, so software support isn’t really an issue.
The coating used for the laser printing is sort of like a photo sensitive coating commonly used in photolithography. You apply a coating to the board, apply light to either cure or denature the coating. Then the non-cured or denatured coating is washed away leaving coating everywhere you don’t what etching to happen. After etching this etch mask is removed. The laser method is similar (especially since it is light based), but it doesn’t need a special photo-sensitive coating. Anything that can be burned away by the laser yet would protect the copper from the etchant should work.
Actually removing the copper directly with the laser won’t work for most lasers as copper makes a really good laser mirror, especially for CO2 lasers. (Once when shopping around for a quote on a small custom copper box that I needed, the last laser cutting fab housed that I asked said that it wouldn’t work because their laser’s optical mirrors are copper. I didn’t bother asking any other laser cutting fab houses for a quote after that.)
Seems every time I learn something new about (in this case) PCB making, I always get happily warm and fuzzy about making them on my CNC mill.
• Pretty straight forward for Single and Double sided boards
• THT, SMD, Odd Shapes, Cutouts, Metal/plastic Inserts… list goes on…
All that is easily doable and much faster than any other methods I’ve used. All the holes are auto drilled and I can drink black coffee while waiting.
I haven’t used Laser but have looked into adding Laser Head to my Mill (and 3D printer). I quickly realized the extra steps that would be needed if needing Mounting Holes and THT - many of the parts I use are exclusively THT and I have bins full of them. And, I hate soldering Tiny Parts!!
So, for me, I like milling so much that I’m thinking about buying a $200ish PCB machine for my office (thus avoiding seeing the clutter in my shop LOL).
Just mill it, clean it, dip in (my homemade) tinning solution (link to my post) and wait until I’m not too lazy to solder parts on it
Made several PCB holding fixtures but this one is my favorite - can do any size PCB.
I’d have thought this method would give a pretty rough finish to the edges of the tracks but I’m open to enlightenment.
As for burning off the copper, even if a laser could do the job, the fibreglass base must suffer from some burning also…carbonised fibreglass makes a very good electrical conductor, nearly as good as super glue.
LPKF is producing laser etching machine, if I remember correctly it uses 2nd harmonic Nd:YAG, I don’t remember power density.
If the laser pulse is short enough the thermal effects are minimal, e.g. there is no burning of the laminate. The material either sublimates for the fastest pulses or makes a explosion of droplets and chunks for slower pulses.
It is not an amateur machine in both price range and specifications, and also there is a severe danger of loosing Your eyes if trying to do something like that ta home. If possible use a pcb engraving using CNC engraver machine, but be aware that the FR4 is made of fiberglass, e.g. make some vaccum cleanrer systenm and do be aware of noise levels.
